A291847 A diagonal of irregular triangle A291845.

1, 4, 26, 224, 2389, 30324, 446109, 7460928, 139775763, 2899264620, 65954625560, 1632654953280, 43688087178059, 1256602120453484, 38661480001233486, 1266934683224418816, 44054989554206606603, 1620147926716343851500, 62826169539072988352134, 2562071016044926371845920, 109611597248567432265872903, 4908887251696851858305862332

Offset

0,2

Comments

G.f. of row n in triangle A291845 equals Product_{k=0..n-1} (1 + (2*k+1)*x + x^2), with row sums equal to the odd double factorials A001147.

Links

Paul D. Hanna, Table of n, a(n) for n = 0..300

Formula

a(n) = A291845(n+1,n).

Prog

(PARI) /* As a Diagonal in Triangle A291845 */
{A291845(n, k)=polcoeff(prod(j=0, n-1, 1 + (2*j+1)*x + x^2), k)}
{for(n=0, 25, print1(A291845(n+1, n), ", "))}

Crossrefs

Cf. A291845, A291846, A291848.

Sequence in context: A371539 A245768 A152407 * A168448 A105616 A293915

Adjacent sequences: A291844 A291845 A291846 * A291848 A291849 A291850

Keyword

nonn

Author

Paul D. Hanna, Sep 03 2017

Status

approved